The present invention relates to a slit shutter device for a camera. It comprises a first cover system which uncovers the usual image window during an exposure, and another cover system operating this system after a time delay to close the window again.
Slit shutters of this general type are known in many different embodiments. One type of shutter was provided with cover systems with cloth rolls; but when the disadvantages of such roller blinds were recognized, slit shutters were developed, the cover systems of which include a plurality of slides associated with each other for relative movement. Conventional slit shutters of this type have the disadvantage, however, that the slides cannot be rapidly accelerated because of their weight and size, so that shutter speeds of the type required, for example, for making day-light exposures of extremely rapidly moved objects, or electronic flashlight exposures, cannot be achieved. Another disadvantage of these slit shutter arrangements is that they require a relatively large amount of space, with the result that difficulties of design arise, particularly with vertically operating shutter members.
The main object of the present invention is to produce a slit shutter for a photographic camera. Such a shutter comprises one cover system uncovering the image window during exposure and another cover system following the first system after a selectable time delay for covering the window again. Each of the two cover systems includes a folding blind, which is fixed at one end and is connected at the other end to a rigid rail forming one edge of the slit and displaceable along a straight line.
A particular advantage of this invention is that only relatively small masses have to be accelerated during an exposure since the cover system from an extended condition folds together, and in the folded condition needs only to be extended, so that it is only necessary to move a mass progressively diminishing from a maximum value. In addition, it has been possible to dispense with complicated guide members which are unavoidable in conventional slit shutter arrangements, and consequently there is a considerable reduction of parts.
According to a preferred embodiment of the invention, the folding blinds are formed of a buckle-proof flexible material, such as a cloth provided with a rubber layer. According to a further feature of the invention, a folding blind consists of identical strip-like members articulated together.
In order to prevent the entry of light and curling-up of the curtain during the folding operation, it is also proposed in accordance with the present invention that the folding blinds may be located between plates, the depth of which is approximately the width of the blind in the folded-up condition. The plates are preferably of L-shaped section and enclose the edges of the folding blinds. Preferably displaceable rails provided for each cover system form the edges of the slit, and are connected to the ends of links of a parallel linkage.